Utjecaj odabranih sojeva vinskih kvasaca na vezanje, razgradnju i toksičnost okratoksina A u in vitro uvjetima

doctoral thesis

• Title (english): Effect of selected wine yeast strains on binding, degradation and toxicity of ochratoxin A in vitro
• Author: Željko Jakopović
• Mentor: Ksenija Markov (mentor)
• Committee member: Jadranka Frece (član povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Biochemical Engineering); (Laboratory for General Microbiology and Food Microbiology); Zagreb
• Defense date and country: 2021-10-07, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Biotechnology
• Universal decimal classification (UDC): 577 - Biochemistry. Molecular biology. Biophysics

Abstract

Okratoksin A (OTA) se u značajnim koncentracijama pojavljuje i u vinu pa se za njegovo uklanjanje primjenjuju različite strategije. Cilj ovog rada je bio odabrati sojeve vinskih kvasaca koji će razviti specifičan odgovor na OTA, pri čemu će ga razgraditi ili modificirati u manje toksične produkte. Dobiveni rezultati ukazuju da su kvasci razvili mehanizme prilagodbe na uvjete u kojima je prisutan mikotoksin, jer koncentracija OTA nije značajno utjecala na veličinu i broj živih stanica kvasaca kao ni na koncentraciju produkata fermentacije. Na parametre oksidativnog stresa u stanicama kvasaca djeluje prisutnost OTA u YPG mediju, a što se vidi iz povećanja koncentracija gluatationa (GSH) i malondialdehida (MDA). Na njihove povećane koncentracije mogu utjecati i drugi parametri poput kombinacije vremena trajajanja uzgoja i različitih sojeva kvasaca. Uočeno je da početna koncentracija OTA ima značajan utjecaj na koncentraciju OTA koji zaostaje u mediju. Kao najbolji soj za vezanje/uklanjanje OTA pokazao se Saccharomyces cerevisiae 5 koji je u ovisnosti o koncentraciji OTA (2, odnosno 4 μg mLˉ¹) nakon 24 sata uzgoja vezao 38, odnosno 36 % OTA. Nadalje, razgradnja OTA do okratoksina C (OTC) ovisna je o vremenu uzgoja, a početna koncentracija OTA ima značajan utjecaj na koncentraciju nastalog OTC. Najbolju sposobnost biorazgradnje OTA do OTC (0,737 μg mL-1 ) nakon 12 sati uzgoja pokazao je kvasac Saccharomyces uvarum. OTA u koncentracijama 2 i 4 μg mLˉ¹ kao i nastali OTC nisu toksični prema Pk15 stanicama, budući da su stanice pokazale visoku stopu preživljenja (98 – 99 %).

Abstract (english)

Ochratoxin A (OTA) also occurs in significant concentrations in wine, so various strategies are used to eliminate it. The aim of this study was to select strains of wine yeast that will develop a specific response to OTA, by degrading or modifying it into less toxic products. The obtained results indicate that yeasts have developed mechanisms of adaptation to conditions in which mycotoxin is present, because the concentration of OTA did not significantly affect the size and number of living yeast cells not the concentration of fermentation products. The parameters of oxidative stress in yeast cells are affected by the presence of OTA in the YPG medium, which can be seen from the incease in the concentrations of glutation (GSH) and malondialdehyde (MDA). Their increased concentrations can be affected by other parameters such as the combination of cultivation time and different strains of yeast. It was observed that the initial OTA concentration has a significant effect on the residual OTA concentration in the medium. Saccharomyces cerevisiae 5 proved to be the best strain for binding/removing OTA, which, depending on the concentration of OTA (2 and 4 μg mL-1) after 24 hours of cultivation, bound 38 and 36 % OTA, respectively. Furthermore, the degradation of OTA to ochratoxin C (OTC) is time-dependant, and the initial concentration of OTA has a significant effect on the concentration of the resulting OTC. The best ability to biodegrade OTA to OTC (0.737 μg mLˉ¹) after 12 hours of cultivation was shown by the yeast Saccharomyces uvarum. OTA at concentrations of 2 and 4 μg mLˉ¹ as well as the resulting OTC are not toxic to Pk15 cells, as the cells showed a high survival rate (98 – 99 %).

• Keywords: biorazgradnja; okratoksin A; toksičnost; vezanje; vinski kvasci
• Keywords (english): biodegradation; ochratoxin A; toxicity; binding; wine yeasts
• Language: croatian
• URN:NBN: urn:nbn:hr:159:380714
• Promotion: 2021
• Study programme: Title: Postgraduate PhD Study in Nutrition; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje biotehničkih znanosti, polje nutricionizam (doktor/doktorica znanosti, područje biotehničkih znanosti, polje nutricionizam)
• Type of resource: Text
• Extent: 133 str. : 30 cm.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2021-11-24 14:30:12